Black Rhodium Tank Plating Solution (UK and EU only)

£230.98£858.40 + VAT

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Black Rhodium Tank Plating Solution can plate durable black layers of rhodium and offers the following advantages:

  • Easy to operate.
  • Can be operated at room temperature without agitation – no need for hotplate/stirrers.
  • The process can be controlled using our Black Rhodium Online Calculator.
  • Blackness can further be enhanced by special treatment after plating. However close adherence to the method is essential. Please read Tech Specs for further information.

Orders outside UK and EU

This plating solution cannot be shipped outside the UK and the EU because it’s part of our range of plating solutions which are regulated for transport.


HS Code: 3824 99 70

The ring on the right has been plated with our black rhodium tank plating solution and been  further enhanced by special treatment after plating. The ring on the left has been plated with our Anthracite Grey Rhodium Tank Plating Solution

Our black rhodium tank plating solution is an excellent replacement for other less robust blackening agents.

This silver ring has been selectively black rhodium and yellow gold plated and then the black rhodium layer has been gently rubbed back with a glass brush, to bring out the textured surface. Unlike other blacking agents, the black rhodium layer won’t rub off so quickly.

Here’s a video showing how to use our black rhodium tank plating solution and equipment;

Here’s a quick video to show how to deepen the blackness of the black rhodium post plating in our Cleaner.
Please refer to Tech Specs for more on this process:

Here’s a video showing how to clean the surface of your work so that it’s water break free and ready for plating;

Back to Product Description

Surface preparation for electroplating - achieving a water break free surface

There are two main stages in preparing the surface of your work for electroplating;

1. The polishing stage
2. The cleaning and /or activation stage.

For the polishing stage you can choose either a) hand polishing or b) machine polishing.

For the cleaning stage there are a couple of routes you can go, depending on the condition and type of surface you're intending to plate. Whichever route you choose, you need to achieve a water break free surface at the end of the cleaning process as this is one of the best ways of ensuring an excellent plating result.

The following guidance is good for all three plating techniques - pen, brush and tank electroplating.

Many problems with electroplating occur because the surface wasn't prepared well enough. Once this stage is sorted, you'll get good electroplating results at the end!

Stage One - Hand and Machine Polishing

a) Hand Polishing

If you’re electroplating small, slightly scratched items, we recommend starting off with an abrasive polish, for example, Autosol. The traces of these types of abrasive polishes will need to be removed with solvent or if this isn’t available you can use our MetaPrep. The MetaPrep or solvent will then need to be removed with liquid detergent and then rinsed very thoroughly under running water. You can then move on to our MPU using tissue paper. For in-depth guidance on hand polishing, please click HERE for our ‘Polishing metal for electroplating’ page.

Stage One - Hand and Machine Polishing

b) Machine Polishing

This approach to polishing is only necessary if the item you’re electroplating is quite large and deeply scratched.

First, some safety advice;

•Wear a visor, gloves and tie loose hair back. Don’t wear loose fitting clothing or jewellery.

•Bring the work up to the mop, using only the bottom section.

You may have to work through two or three stages of polishing, changing mops and corresponding polishing bars. The table below gives guidance on which polishing bar to choose. To see examples of the various mops and polishing bars, refer to the in-depth section on polishing further on in this manual. Once the item is polished, go onto the cleaning/degreasing stage.

Surface of work Type of polishing bar Type of mop
For very deep scratches Grey bar Sisal
For medium scratches Green bar Stitched
For the final polishing Blue bar Loose leaf

Stage Two - Cleaning/Activating

Cleaning means removing all dirt and oil. Activating means removing the oxide layer that builds on metal, particularly with stainless steel, nickel and nickel containing alloys such as nickel silver. You may have to have a separate cleaning and activating stage, if your work is made of stainless steel, nickel or nickel containing alloys.

Here are the steps you need to go through for this stage of the surface preparation process;

If you have machine polished or hand polished with Autosol, clean the traces of polishing compound off with a solvent or MetaPrep and then remove all traces of solvent or MetaPrep with liquid detergent. Rinse off all traces of detergent thoroughly under running water so that no suds remain.

Then if your work is small to medium sized and has a fairly smooth surface and isn’t made of stainless steel, nickel or nickel containing alloys, finish the cleaning/activating stage with MPU. This cleans away all remaining traces of oil and activates the surface at the same time.

However, if your work is made of stainless steel, nickel or nickel containing alloys, is very large or has a very uneven surface, use our ActiClean to clean and activate in one. Use a Carbon Electrode (preferably) or a Platinum Electrode.

A Water break free surface

The ultimate aim of polishing and cleaning/activating is to make a water break free surface, as illustrated in the picture to the right.

On the top half of the copper sheet, the surface isn’t completely clean and so the water is gathering up into droplets and staying on the surface of the metal.

However, on the bottom half of the copper sheet the water has completely drained off the surface as it is completely clean and doesn’t provide anything for the water to cling to or gather around. This is a water break free surface and is ideal for effective electroplating. This should happen after you’ve completed stage 1 and 2 above.

How to use this calculator :

1. In the first box enter the temperature at which you are plating.

2. In the second box, enter the surface area of the article in square centimetres (cm2).

3. Click the ‘Calculate’ button.

4. Read off the amp setting for your rectifier, the plating time and the volume of replenishers to add before starting the plating sequence.

5. The weight of rhodium plated and the approximate cost of the job is included in the final two readouts.

Operating Parameters

Rhodium concentration 2 g/l
Plating Factor 0.02 A/cm2
Plating rate (Plating Factor: 0.02 A/cm2, 20 °C) 0.01 µm/min
Plating rate (Plating Factor: 0.02 A/cm2, 35 °C) 0.031 µm/min
Recommended plating thickness 0.2 micron
Voltage 1-3 volts
pH <1.0
Temperature range 15 – 40 °C
Anode Platinised titanium or MMO (mesh)
Rhodium content in plate 99.1
Blackness L* (CIE Lab measure) Below 50 – 55 (See notes)
Agitation No agitation
Hardness ~400 Hv
Stress (tensile) Very high (brittle)
Special storage requirements None
Shelf life Up to 1 year (without additions)
Health and Safety classification Irritant
Special considerations None
Transport (UN number) 2796



  • Plating rate increases with temperature
  • Coating begins to haze over 0.25 microns
  • Blacker coatings are obtained at lower temperatures.
  • Blackness can be controlled using Black Rhodium Tank Blackening Agent.
  • Deep black coatings (L* < 35) are possible by anodic treatment after plating in Cleaner
    at 3 volts for 1 minute.
    This treatment also vastly improves the layer’s wear and tarnish resistance.
    A protective layer of 0.5 micron of gold should be applied to the object before black
    rhodium plating when performing anodic treatment.
  • Cover the solution when not in use and if not using for a long period of time, store in a closed

Some items are regulated for transport and can only be delivered to destinations in the UK and countries within the EU. Alternative or substitute products are detailed in the ‘Description’ tab of this tabbed panel or under Related Items below this tabbed panel.
For all price quotations for deliveries, please add your items to our shopping cart. You will be able to see the shipping costs by clicking on the ‘Calculate shipping’ button in the cart and before checking out.

You can access our MSDS by scanning the QR code which is on our product bottles.
Here is a video to show you how;